Generally, a process of manufacturing a dental prosthesis in a dental clinic includes removing a damaged tooth, obtaining an engraved dental model by taking an impression of a removed tooth and surrounding oral tissues using an impression material, casting an embossed tooth model by injecting plaster into the engraved dental model, obtaining digital three-dimensional surface data is obtained through 3D scanning and surface rendering of the embossed dental model, and designing the prosthesis using CAD/CAM system and processing appropriate material according to its surface coordinates.
However, of the above processes, there is a possibility that errors in actual teeth may occur during the process of taking the impression, the process of obtaining engraved and embossed dental models based on the impression, or the process of scanning the dental model. The surface coordinate data used to manufacture the final prosthesis is obtained from the dental model, not the actual tooth, wherein the volume data of the actual teeth is obtained mainly through the dental X-ray imaging apparatus, whereas the surface data of the dental model is obtained through a separate scanning device, so data verification is difficult.
For this reason, as disclosed in the documents of Korean Patent Application Publication No. 10-2011-0020323 and Korean Patent Application Publication No. 10-2010-0070822, an attempt was made to acquire a surface image of a tooth from an X-ray image of a subject's teeth directly imaged by using a dental X-ray imaging apparatus and utilize it in the manufacture of a prosthesis. However, in order to obtain a suitable level of image for the CAD/CAM system, the X-ray imaging time becomes long, which causes a problem of increasing the radiation dose. The quality of the imaged image may be deteriorated or error may occur due to the movement or vibration of the subject during the imaging time.
Meanwhile, an intraoral scanner is also used to directly acquire three-dimensional surface data of the patient's intraoral structure. However, the intraoral scanner requires not only two or more skilled radiographers but also the inconvenience that the patient has to open his mouth for a long time. Further, it is problematic in that due to the limitation of the intraoral scanner using the reflected signal, the accuracy of the data for critical areas, such as the interdental area or gingival boundaries, in the treatment plan is reduced.